Pobation of geemany



May 12, 1925.,

W. OHNESORGE RECIPROCAL TELEPHONE REPEATER Filed Aug. 30, '1921 Patented May 12, 1 925.

PATENT OFFICE.

UNITED STATES WILHELM OHNESORGE, OF DORTMUND, GERMANY, ASSIGNOR TO SIEMENS & HALSKE,

AKT'IE'NGESELLSCHAFT, OF SIEMENSSTADT, NEAR BERLIN, GERMANY, A COB- POR-ATION OF GERMANY.

RECII'ROCAL TELEPHONE REPEATER.

Application filed August 30, 1921. Serial No. 496,916.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT; L, 1818.)-

1915, Patent No. 302,402), of which the following is a specification.

All systems for the operation of reciprocal telephone repeaters were hitherto based on 'the principle of line balance. The repeater was connected into the circuit in such a way that it received current from each of the line sections connected together and, under the influence of this current, transmitted an uniformly amplified current into the other line section. It was necessary to balance the line in order to prevent the repeater to be influenced by the amplified current which it has produced itself, thus giving rise to a permanent tone.

The balanced connection is always accompanied by great draw-backs, no matter whether it is arranged as difierential or as bridge connection. The lines coupled through the intermediary of this connection alter their electric properties-chiefly under unfavourable weather conditions-almost continually so that balance can only be maintained to a limited degree by means of continuous regulations of additional equipment, such as artificial conductors, weakening-resistances, for the receiver or transmitter part of the repeater and similar arrange ments. This results in Whistling or grating noises which disturb the conversation. Moreover, the balanced connection materially reduces the efliciency of the intensifier, e. g. with the customary arrangements 'of "operation down to 30%. o

In order to overcome the drawbacks outlined above it is necessary to revert back to the one way amplifier connections, i. e. torepeaters connected in such a way that in the first section of the line it is. only located with its receiver side, whereas in the other section it is located with its transmitter side. It is obvious that with this connection one line can only be used for talking in one direction, i, e. from A to B not, however, from B to A. If it is desired to maintain a proper conversation also from B to A, it is necessary to have two lines between these points. This means that the cost of line construction is thereby doubled. In order to be able to carry on a proper conversation with repeater only on one side, by using one line only, the following arrangement is proposed accordlng to this present invention; in which- 7 Figure 1 represents a curve diagram;

Figures 2 and 3 show a commutator and itsdconnections according to my invention; an

Figure 4 shows a modification thereof.

The two sections of the line, one of which s placed in the receiver part and the'other 1n the transmitter part of the repeater are exchanged the one for the other in rapid successlon by means of an automatically rotatng commutating gear. If for instance during the first, very small time interval, e. g. for one hundredth part of a second (or, whatever other fraction of a second may be desirable and practical) the first section had been connected to receiver part, the second section to the transmitter part, of the repeater, then in the second hundredth part of a second the second section is changed over to the receiver and the first section to the transmitter part. During the third time interval of one hundredth of a second the connection as during the first time. interval is reestablished, and so forth. The rotating speed of the contact device and, therefore, the time intervals of the disposition of the two sections of the line on one direction or other, must be selected in such a way that certain portions of the speaking curves dropping out (of. Fig. 1) will not be able to alter the character of this curve and that, nevertheless, the limit of sensitiveness of the apparatus is not exceeded.

With these and other objects in view, the invention will be hereinafter more particularly described with reference to the accompanying drawings forming part of this specification and will then be pointed out in the claims at the end of the description.

Figs. 2 and 3 represents an example of how the present invention may be carried 'out.

The two lines which are coupled together by a repeater of the known type, terand f ter side, connection is established with the contacts 0 b 0 6,, etc., or respectively d a d 0 etc. From'this numbering, the connection of the lines for each position of the contact springs becomes absolutely clear.

A difierent method is represented in Figure 4.

In this case the repeaters or relays '0 and o, are with their receivers c and e respectively, and their transmitters s, and 8 respectively, permanently connected to the respective sections of the line. Only the input sides of the repeaters are alternately short-circuited by the contact device. In this manner, whilst the first repeater works in one time interval, the second repeater is rendered insensible to the influence of the outgoing amplified current by short-circuiting its receiver side. During the next time interval the opposite takes place namely, the second repeater is working whilst the first is put out of operation by short-circuiting its receiver side, and so forth. It is obvious that in place of the relays represented on the drawing, thermionic relays may also be used.

I claim 1. In a reciprocal telephone repeater system the combination of the repeater connection with commutating means adapted to alternately put said repeater connection into and out of operation, for either the one or other direction ofspee-ch, at a suitable speed at which the clearness of the telephonic conversation is not affected.

2. In a telephone repeater system the combination of the repeater connection with one amplifier for each direction of speech, with means for alternately short-circuiting the input side of each amplifier.

In testimony whereof I aflix my signature. I

WILHELM OHNESORGE. 

